Molding outer and inner soles onto shoe uppers

ABSTRACT

A process for molding an outer sole of elastomer and an inner sole of a mixture of isocyanate and a polyol reacting into polyurethane to shoe uppers includes a vertically movable upper cross block supporting a pivotably mounted mold carrier with a heatable first mold part at one end for the molding of outer soles, and a lower, vertically adjustable cross block has a mold plate confronting the first mold part. The first mold part releases the molded outer sole on to the mold plate, the mold carrier is pivoted such that a cooled second mold part at the opposite end thereof overlies the molded outer sole which is then transferred to the second mold part, the mold carrier is again pivoted to confront the molded outer sole to a shoe last supported shoe upper, and an inner sole mold cavity is formed with the molded outer sole juxtaposed to the last supported shoe upper, and by an opposed pair of lateral mold elements closed about the shoe upper.

RELATED APPLICATIONS

This application is a divisional application of application Ser. No.116,361, filed Nov. 4, 1987, now U.S. Pat. No. 4,801,256.

This application relates to U.S. Ser. No. 116,666 filed on even dateherewith, now U.S. Pat. No. 4,810,178, corresponding to Germanapplication Nos. P 36 438 22.7-26 and P 36 37 696.5-26, respectivelyfiled Dec. 21, 1986 and Nov. 5, 1986, relates to commonly assigned U.S.Ser. No. 135,369 filed Dec. 21, 1987, corresponding to Germanapplication No. P 36 438 20.0-26, filed Dec. 20, 1986, and furtherrelates to commonly assigned U.S. Ser. No. 942,832, filed Dec. 17, 1986now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to the molding of outer and inner soles onto shoeuppers, the outer sole consisting of an elastomer material and the innersole consisting of a thermoplastic material, the inner and outer solesbeing joined together by a chemical bond between isocyanate contained inthe thermoplastic material and reactive end group substances added tothe elastomer. The apparatus has a vertically moveable upper cross blockwith a mold carrier mounted thereon for pivotal movement about atransverse axis, the mold carrier having a heatable first mold part atone end for the molding of outer soles in a molding position of theapparatus. A vertically moveable lower cross block has a mold plate inengagement with the first mold part in the molding position. Thepivotable mold carrier together with lateral mold elements of theapparatus and a shoe last-mounted shoe upper cooperate together todefine a cavity for the molding of the inner sole.

The molding apparatus may be located at each of a plurality of moldingstations on a circular turntable for carrying out the molding operation.

German patent No. 22 41 493 discloses shoes with an inner sole ofpolyurethane and an outer sole also of polyurethane.

Circular turntable installations providing a plurality of moldingstations are generally disclosed in Publication No. DESMA 521S-526S,Klockner-Ferromatik Desma GmbH, and entitled "Injection Molding MachineFor Direct Attachment Of Soles." The circular turntable installationshave two devices for the mixing of isocyanate and a polyol into amixture reacting into polyurethane which, depending on the mixing ratioand the additives, reacts into a wear-resistant outer sole or a flexibleinner sole.

The circular turntable is rotated incrementally for molding the outersoles and the inner soles. The molding stations are stopped duringincremental movement and interlocked when stopped relative to the twomixing and injection devices.

These devices are located along the periphery of the turntable and aremovable in a radial direction toward the turntable. The moldingapparatus at each station has two lateral molding elements which, in amold closed position, define an opening and two sprue channels.

A vertically moveable last turning body is mounted on the apparatusabove the lateral mold elements, the body having a counterstamp and ashoe last for supporting the shoe uppers.

A vertically adjustable bottom stamp is located below the lateral moldelements. The bottom stamp, lateral mold elements in their mold closingposition and the counterstamp together define a mold cavity into whichthe mixture reacting into the outer sole is introduced.

The bottom stamp which contains the molded outer sole, the lateral moldelements in a mold closed position, and the shoe last which supports theshoe upper together define a mold cavity for molding the inner sole asthe mixture reacting into the inner sole is introduced into the moldcavity which, in the course of the reaction, bonds to the outer sole andto the shoe upper.

U.S. Ser. No. 942,832, among the aforementioned related applications,discloses molding stations on a circular turntable for the molding ofshoe soles with an outer sole of elastomer and an inner sole ofpolyurethane.

For the molding of the outer sole of elastomer, there is provided, inlieu of a previously employed device for mixing the mixture reactinginto polyurethane, a plastification and injection aggregate device forplastification of the elastomer, as employed in injection moldingmachines for the processing of thermoplastic synthetic materials, andfor injection of the elastomer into the outer sole mold cavity. Sincehigh pressures occur during the injection of the plastified elastomer,the molding apparatus at each station is provided with an upper,vertically adjustable cross block supporting a pivotably mounted moldcarrier with pairs of opposing heatable mold parts lying parallel to thepivot axis, each mold part defining a mold cavity for the outer sole andincluding cooling channels.

A lower, vertically adjustable cross block below the first cross blockhas a heatable plate facing the mold carrier and cooperates with theheatable mold parts thereof for the production of outer soles. Above theupper vertically moveable cross block is a fixed cross block having anopening into which a heatable mold part with a molded outer sole in itsmold cavity projects and combines together with laterally movable moldelements, located above the fixed cross block, for the molding of aninner sole of polyurethane.

The mixtures which react into polyurethane for the outer sole and/or forthe inner sole essentially consist of a polyol and isocyanate, as wellas chain extenders and catalysts, which are adjusted by the respectiveadditives for the desired material properties of the outer soles and/orinner soles, whereby the outer sole is rendered wear resistant and theinner sole flexible having a porous structure.

The chemical reaction starts with the mixing of the components. In themold, the mixtures react into outer soles or inner soles. During thereaction into the inner sole, the molding of the sole takes placesimultaneously with the bonding to the shoe upper and to the outer sole.

The outer sole of elastomer and the inner sole of polyurethane arebonded in the area of their contacting surfaces by chemical bondsbetween isocyanate and reactive end groups of the substances added tothe elastomer.

As likewise employed for the present invention, the mixtures reactinginto polyurethane are mixtures on the basis of ether or esterpolyols,containing on the basis of 100 parts by weight:

30-100 parts by weight isocyanate;

0.1-10 parts by weight catalyst;

the remainder chain expanders; and

other usual additives.

The catalyst which may be used is DABCO-SB produced by AirproductsCompany.

The outer soles are made from elastomers which can be mixed with thefollowing chemical compounds or chemical substances in quantitativeshares of 0-20 phr, relative to the rubber amount: e.g.,acryl-nitryl-rubber, styrol-butadiene-rubber, natural rubber,chloroprene-rubber.

The outer soles can generally be produced from any known rubberquantities if, for example, the following substances are mixed inquantities of 0-20 phr (quantity relative to the amount of rubber used):

phenolformaldehyde resins, e.g.

Vulkadur A (Bayer AG)

Coretack (BASF)

methylolized phenolformaledhyde resins, e.g.:

SP 1045 (Krahn)

Korever (BASF)

resorcin in connection with a formaldehyde dispenser, e.g.:

Cohedur A (Bayer AG)

Cohedur RS (Bayer AG)

Cohedur RK (Bayer AG)

silicic acid fillers, e.g.:

Vulkasil S (Bayer

Ultrasil (Degussa)

aminoalcohol, e.g.:

3-amino-propanol

primary or secondary amine, e.g.:

Stearylamine

polyvinylalcohol, e.g.:

Mowiwol (Hoechst)

VSH 72 (AIR PRODUCTS)

VSH 73 (AIR PRODUCTS)

high hydroxylgroup containing polyol, e.g.:

Formrez (Witco)

Acrylate rubber (ACM) e.g.:

Hydrin (Polysar)

Hercolor (Hercules)

or a combination of the above substances.

The formation of the outer sole of the elastomer is carried out in sucha manner that the elastomers plastify at the usual processingtemperatures and are injected into the mold cavities according to theusual technology and corresponding high pressures of injection moldingmachines.

The control of the temperature of the elastomers is carried out suchthat the temperature of the injected outer soles is cooled to just belowthe decomposition temperature of the polyurethane for the inner sole tobe produced and then the mixture reacting into the polyurethane isbrought into contact with the outer sole, whereby in the contactingsurfaces between the elastomer and the reacting polyurethane isocyanatereacts with the reactive end groups.

Taken into account in the control of the temperature of the elastomer isthat a temperature increase or a temperature reduction of 10° C. leadsto a shortening or lengthening of the vulcanization time, i.e., the timeneeded for the elastomer to complete its reaction, by 50%.

One of the problems encountered with the molding apparatus of theaforementioned published application is that the cooling rate of themolded outer sole of elastomer to the temperature at which the mixturereacting at the polyurethane for the inner sole is introduced into themold cavity for the inner sole is essentially determined by the highheat capacity of the mold parts located on the pivotable mold carrier.This cooling rate has the effect that the time required for the moldingand cooling of an outer sole is considerably longer than the timerequired for molding the inner sole.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to mold outer andinner soles on to shoe uppers in a manner to ensure sufficient coolingof the molded outer sole during the simultaneous molding of the outersole of elastomer and an inner sole of polyurethane.

Accordingly, the pivotable mold carrier of the present invention mountedon an upper vertically adjustable cross block has a heatable first moldpart at one end in engagement with a heatable mold plate of a lowervertically adjustable cross block defining a mold cavity for the outersole of elastomer to be molded. The mold carrier having a cooled secondmold part at its opposite end works together with closed lateral moldelements and a shoe last-mounted shoe upper which together with analready molded outer sole defines a mold cavity for the inner sole. Ashoe last holder is mounted above the lateral mold elements for verticalmovement between extended and retracted positions, and may further bemounted for pivotal movement about a transverse axis. The last holderhas a shoe last for supporting a shoe upper. The first mold partreleases the molded outer sole on to the mold plate, the mold carrierpivots such that the second mold part overlies the released molded outersole, and removes the outer sole from the plate by suction. The moldcarrier pivots and brings the second mold part with the retained moldedouter sole into juxtaposition with the last supported shoe upper. Themold carrier is shifted toward the shoe last so that the inner sole moldcavity is formed. Polyurethane injected into the inner sole mold cavitychemically bonds to the elastomer and bonds to the shoe upper.

The molding apparatus of the invention may be mounted on a circularturntable at each of several stations, so that the incremental movementsof the turntable may be synchronized with the injection intervals of theelastomer and polyurethane into the outer sole and inner sole moldcavities. The inner and outer soles may therefore be moldedsimultaneously. And, the times for vulcanizing and cooling the outersoles injection molded from elastomer are separate, so that the outersoles may be vulcanized in the closed and heated mold during a givennumber of incremental turns of the turntable, and the mold thereafteropened only when moved into a working position shortly before it reachesthe device for mixing and injecting the polyurethane.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top plan view of a circular turntable showing aplurality of stations at each of which an apparatus according to theinvention is located, an injection device for the outer sole materialand a mixing/injection device for the inner sole material being shownrelative to the turntable; and

FIGS. 2 to 6 are schematic views in side elevation of the details of thepresent apparatus illustrating the various operations of the moldingapparatus carried out during the molding operation.

DETAILED DESCRIPTION OF THE INVENTION

Circular turntable 1 in FIG. 1 illustrates 14 molding stations 2arranged equally spaced and schematically illustrated by squares. Thesquares also illustrate the positions which the molding stations assumeduring the incremental rotation of the turntable. With the presentarrangement, each mold station will reach its original position after 15incremental turns of the turntable. The positions are designated 2₀₁ to2₁₄.

A radially disposed plastification and injection aggregate device 3 foran elastomer is located adjacent the periphery of the turntable. Aftereach incremental movement of the turntable, i.e. equal to a 1/14 thturn, device 3 is locked in some normal manner relative to one of themolding stations 2 shown in position 2₀₁, and is capable of shiftingradially relative to the turntable. When the device 3 is interlockedwith the mold station, elastomer for the outer soles is injected intothe mold cavity of the apparatus.

Also arranged in a radially shiftable manner relative to the turntableis a device 4 for the mixing of the mixture reacting into polyurethane.After each incremental turn of the turntable this device can also beinterlocked with one of the work stations which had been rotated to thecorresponding work, station 2₀₃, so that material for molding the innersole is injected into the mold cavity of the apparatus. Depending on thereaction or vulcanization time of the materials used, the two devicescan be interchanged from that shown.

Molding apparatus 2 is shown in detail in FIGS. 2 to 6 in variousworking positions as viewed in the direction of the single arrows ondevices 3 and 4.

The mold parts for molding apparatus 2 of FIG. 2 for the molding of theouter sole and for the molding of the inner sole are shown in closedposition.

The apparatus has a generally upstanding frame structure which includesfour spaced upstanding guide posts 5, of which only two are visible. Alower fixed cross block 6 and an upper fixed cross block 8, having acentral opening 7, form a fixed guide frame together with guide posts 5fixed at opposite ends to blocks 6 and 8. An upper, vertically movablecross block 9 is mounted for sliding movement along guide post sections5a of smaller diameter compared to guide post sections 5b. A moldcarrier 11 is mounted on block 9 for pivotable movement about thecentral axis of transverse bolt 10. A lower, vertically moveable crossblock 12 is arranged for sliding movement along larger diameter sections5b of the guide posts.

Hydraulic or pneumatic piston and cylinder units 15, 16 extend betweencross blocks 12 and 6 for vertically moving both cross blocks 9 and 12into the mold closing position of FIG. 2 in which mold carrier 11 isfully extended so as to bear against cross block 8 adjacent its centralopening. A mold locking cylinder 13 operating between blocks 6 and 12locks the cross blocks in the mold closing position. And, a heatableplate 14 mounted on cross block 12 bears against one end of the moldcarrier in the FIG. 2 position.

The mold carrier has a heatable first mold part 17 at such one end witha cavity 18 sized to that of the outer sole to be molded. The heat plate14 bears against this mold part 17 in the mold closed position of FIG.2, and a back up heat plate 19 is secured to mold part 17 and isattached to the mold carrier via an insulating layer 20.

The mold carrier has a second mold part 22 at its opposite end formedwith a mold nest 23, and an insulated cooling plate 21 interconnectingmold part 22 to the mold carrier. The cooling plate may be provided withpassages (not shown) through which a cooling medium flows. And, moldnest 23 is sized to the dimension of the molded outer sole.

Mold part 22 has a plurality of suction channels 31 (only one beingshown for clarity) connected to a vacuum source (not shown) forsuctioning the molded outer sole for supporting it in cavity 23 duringpivotal movement of the mold carrier, as will be described in moredetail hereinafter.

A pair of opposing, laterally movable side mold elements 24, 25 aremounted on the upper surface of cross block 8. Suitable actuation means,such a D₁ schematically shown in FIG. 3, is provided for shifting thelateral mold elements between open and closed positions. In the moldclosed position of FIG. 2, the closed mold elements 24, 25 together witha shoe upper 27 supported on a shoe last 26, and mold part 22 containingan already formed outer sole (as will hereinafter be more fullydescribed in detail) define a mold cavity for the molding of the innersole.

As high peak pressures occur during the injection of outer soles ofelastomer, comparable to those peak pressures which take place ininjection molding machines for the processing of plastic material, theusual drive cylinders and mold locking cylinders are required similar tothose employed in such injection molding machines.

During injection of the plastified elastomer into mold cavity 18 in themold closed position of FIG. 2, wherein the mold cavity is delineated byheatable plate 14 and mold part 17 in the closed position, the reactionforce applied to the frame is taken up by cross blocks 6 and 8 aspivotable mold part carrier 11 bears against cross block 8 at thesurrounding area of its opening 7. Coiled pressure springs 30, or thelike, extend between cross blocks 9 and 12 such that the upward verticalmovement of cross block 12 via drive units 15, 16 is transmitted tocross block 9.

A last holder of known construction (not shown), has a last body mountedon the frame structure of the apparatus above cross block 8. Somesuitable means such as a hydraulic piston and cylinder unit D₂ or thelike may be provided to effect vertical adjustment if required. Also,the last holder may be mounted for pivotal movement about a transverseaxis. Shoe last 26 extends from one end of the last body and supports ashoe upper 27.

FIG. 2 illustrates the relative positions of the cross blocks of themolding apparatus 2 at station 2₀₁ (FIG. 1). At station theplastification and injection aggregate device 3 is radially moved towardthe turntable and abuts a pour opening (not shown) of mold cavity 18 forinjecting plastified elastomer into the mold cavity for molding an outersole L. The mold cavity remains closed until, after a correspondingnumber of incremental moves of the turntable, the molding apparatus atstation 2₀₁ has reached station 2₁₁, after passing through stations 2₂through 2₁₀. At station 2₁₁ the Pistons of units 15, 16 are retractedcausing cross blocks 12 and 9 to lower to their FIG. 3 position. Block12 slides along guide post sections 5b, and block 9 slides along guidepost sections 5a and is stopped as it bears against shoulders (notshown), or the like, at the transition between the different diametersections 5a, 5b. Pressure springs 30 Permit block 9 to stop in theposition shown in FIG. 3 while block 12 moves slightly further awaytherefrom to provide a clearance between the mold carrier and heat plate14, as shown. Mold carrier 11 is then pivoted to its FIG. 3 positionthrough 180° by actuation by some suitable drive means D so that coldmold part 22 confronts heat plate 14 and heatable mold part 17 confrontsopening 7 of cross block 8.

In the lowered position of blocks 12 and 9 of FIG. 3, the molded outersole L releases from cavity 18 of the first mold part and rests on moldplate 14, as shown before the mold carrier is pivoted. Thus, mold part22 overlies the released molded outer sole, whereafter blocks 9, 12 areraised to their FIG. 4 position. Suction channels 31 (only one beingshown for clarity) in mold part 22 are connected to some suitable vacuumsource (not shown) for suctioning molded outer sole L to cavity 23 ofpart 22.

Blocks 9, 12 are then lowered to their FIG. 5 position while the blocks9, 12 are again raised. Last 26 is then lowered and mold elements 24, 25are closed, as shown in FIG. 2. The molded outer sole retained in cavity23 of mold part 22, together with the closed lateral mold elements 24,25 and the last supported shoe upper define a mold cavity for the innersole into which the reaction mixture is injected uPon operation ofdevice 4 with the apparatus moved to station 2₀₃.

In the FIG. 2 mold closed position, the molding apparatus is at station2₀₁ such that the elastomer is injected into cavity 18 for moldinganother outer sole simultaneously with the injection molding of theinner sole.

Blocks 9, 12 are then lowered to the FIG. 3 position at which themolding apparatus has been moved to stations 2₁₂, 2₁₃ and 2₁₄ forremoving the finished shoe and mounting another shoe on the shoe lastfor repeating the operation according to the aforedescribed processsteps.

The molding apparatus shown in its FIG. 6 position is located at station2₁₄.

From the above description it can be clearly seen that in the stationaryposition of the circular turntable an outer sole and an inner sole arerespectively injected at the same time and, simultaneously, in the areabetween stations 2₀₄ or 2₁₄ a finished shoe having a molded outer soleof elastomer and a molded inner sole of polyurethane is removed at adischarge station (not shown).

A circular turntable has been described as rotatable through shortincrements, although it is within the scope of the invention to alsoprovide individual mold stations located on a turntable. In sucharrangement, the device 4 for mixing of the mixture reacting into thepolyurethane and the device 3 for the plastification and injectionaggregate for the, elastomer would be arranged above one another.

The mold apparatus according to the invention can employ different moldparts for the vulcanization of the injected outer sole of elastomer andfor the cooling of the vulcanized outer sole, so that the times for thevulcanization and the cooling can be set independent of each other.

Moreover, it is essential that the total time for the vulcanization andcooling of the outer soles until further processing is considerablyshorter than with the use of mold parts which must be heated forvulcanization and then cooled for the cooling of the outer sole.

What is claimed is:
 1. A process for molding outer and inner soles on toshoe uppers, comprising the steps of forming a molded outer sole byinjecting molding an elastomer into a mold cavity defined by a heatablefirst mold part at one end of a pivotable and axially movable moldcarrier and an axially movable confronting mold plate, the injectionmolding being carried out while pressing said carrier against astationary support by moving said mold plate into a mold closingposition against said mold part, releasing the molded outer sole on tosaid mold plate by shifting said carrier away from said support andseparating said mold part into a mold opening position, pivoting saidmold carrier such that a cooled second mold part at an opposite endthereof overlies the molded outer sole, transferring the molded outersole to said second mold part, pivoting said mold carrier to confrontthe molded outer sole to a last supported shoe upper located adjacentsaid support, forming an inner sole mold cavity with the molded outersole by disposing said last supported shoe upper adjacent the moldedouter sole and by closing an opposed pair of lateral mold elements aboutthe shoe upper, forming a molded inner sole by injection molding amixture of isocyanate and a polyol reacting into polyurethane into saidinner sole mold cavity, and thereby bonding the molded inner sole to theshoe upper, the elastomer containing additives of reactive end groups ofsubstances to effect chemical bonding with the isocyanate.
 2. Theprocess according to claim 1, wherein the transferring of the moldedouter sole is effected by suctioning the molded outer sole to saidsecond mold part.
 3. The process according to claim 1, wherein theinjection molding of the inner sole is carried out while again pressingsaid carrier against said support by moving said mold plate into saidmold closing position permitting simultaneous injection molding of theinner sole and injection molding of another outer sole.